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High‐field nuclear magnetic resonance of thallium in zeolites
Author(s) -
Groombridge Christopher J.,
Coker Eric N.,
Rees Lovat V. C.
Publication year - 1993
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260311207
Subject(s) - chemistry , thallium , zeolite , isotropy , anisotropy , magic angle spinning , nuclear magnetic resonance , resonance (particle physics) , analytical chemistry (journal) , nuclear magnetic resonance spectroscopy , inorganic chemistry , stereochemistry , atomic physics , optics , physics , organic chemistry , catalysis
Thallium‐205 NMR is reported for several zeolite samples (A, X and Y; hydrated and dehydrated) with thallium(I) exchanged for sodium. Detection at high field (7.05 T) clarifies the spectrum appearance, and it is seen that chemical shift anisotropy (CSA) dominates some of the band shapes. The large CSAs dictate that the spectrum is recorded piecewise by a frequency‐stepped spin‐echo integral (FUSSI) method. Magic‐angle sample spinning has been observed to give only a very minor line‐narrowing effect. Threefold‐coordinated zeolite A Tl + sites adjacent to six‐membered rings [Tl(1) and Tl(3)] are both assigned to a resonance which has large CSA (δ iso 1183, δδ—1842), while the remaining zeolite A site [Tl(2)] gives an isotropic line shape (δ iso 300). Dehydrated zeolite X gives an isotropic peak (δ iso 854) which is assigned to the double six‐ring Tl(I), and a broader anisotropic resonance which is tentatively attributed to supercage Tl(III). Data for dehydrated zeolite Y indicate that this has a disordered cation distribution.